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Planetary News: Phoenix (2008)Alien Rumors Quelled as NASA Announces Phoenix Perchlorate DiscoveryBy A.J.S. Rayl
The rumors that Phoenix had found something really big had grown so out of control last weekend that they had become something of a big alien snowball headed right toward Washington. So, in a hastily arranged teleconference, Phoenix mission scientists met the press yesterday and reported the much-anticipated discovery. "We have substantial evidence that our soils contain perchlorate, chlorine with oxygen," announced Principal Investigator Peter Smith, of the University of Arizona, from the team's science operations center in Tucson. The immediate implications for life, was "neither good or bad," he added, underscoring this was research in progress. "This does not preclude life on Mars." You didn't even have to have the advantage of videoconferencing to see the look of 'huh' on the faces of the reporters in attendance. Oh, they'd been tipped in the press release issued Monday afternoon – but that was ... it? The wet chemistry laboratory, which is part of the Microscopy, Electrochemistry and Conductivity Analyzer (MECA) instrument onboard the lander had detected perchlorates or mineral salts that contain chlorine and oxygen. Smith and Michael Hecht, a co-investigator and lead scientist for MECA, assured reporters that this didn't really mean anything pro or con as far as the habitability of the soil there or even the potential for some sort of microbial Martian life. "Finding perchlorates is neither good nor bad for life, but it does make us reassess how we think about life on Mars," said Hecht, of the Jet Propulsion Laboratory (JPL), which built MECA. It wasn't that anyone was expecting a little green Martian. But perchlorates? Michael Meyer, the head of the Mars Exploration program at NASA headquarters, previewed the news as the press conference got underway: "We're here today to announce a nonannouncement," he said. "More experiments and time are needed to resolve the results of the science experiments." For the public at large, for the media at large, it was so 'not news' that one reporter lamented: "I don't even understand why there's a press conference today." The reason for the press conference, of course, was to quell the rumors that emanated from a report in Aviation Week & Space Technology (AvWeek) that became so wildly distorted they created an avalanche of misreports and misinformation. The teleconference's purpose was to address the "speculation and rumors" and "to set the record straight," as NASA spokesman Dwayne Brown put it.
To briskly recap the backstory: About two weeks ago, word began circulating among the science media covering Phoenix that the team working on samples with the wet chemistry lab on MECA had found something really interesting and would be making an announcement in a few weeks, once they got confirmation. That scuttlebutt increased in intrigue and the adjectives became more excited during the ensuing week or so, but what exactly MECA had found was still pretty much scuttlebutt and 'mum' was still the word from Phoenix team members. Then, AvWeek published its August 1 report, written by Senior Editor Craig Covault, that began: "The White House has been alerted by NASA about plans to make an announcement soon on major new Phoenix lander discoveries concerning the 'potential for life' on Mars …" By last weekend, tall tales were flying around the Internet. Depending on which report you read, either NASA was going to announce Phoenix had found life or the evidence that showed life was not possible, as was reported here in a news story Monday. In many of the webstories and blogs, the Phoenix team and/or NASA were reported to be holding back, something that implicated the agency was hiding something, ostensibly because the news was so big the President had to be briefed. It appears that the term "White House" in the same context and sentence as a forthcoming NASA "announcement" laid the foundation for fantasy. In a democracy, though, there is supposed to be a constant flow of information from government and civilian agencies to the various levels of government, including the Oval Office; therefore, any time NASA makes a big headquarters-staged announcement, one would certainly hope that the Office of Science and Technology Policy (OSTP) -- created in 1976 to provide the President with timely policy advice and to coordinate the science and technology investment -- would be alerted as a matter of course. In fact, as one scientist put it: "It's S-O-P." Standard operating procedure. And, pertinent to the unfolding scenario, in Covualt's print edition, he reported more ambiguously that the White House had been "notified."
From hungry, creative, and apparently competitive minds, enhanced versions of the "news" hit the world wide web, wherein assumptions emerged and somehow became instant fact. If anything seemed obvious from the Internet play, it's this: there is a lot of interest in planetary exploration, in Mars, and Phoenix – and especially in finding extraterrestrial life. Here's the rub: Phoenix is not designed to look for life, past or present. You would never know that from the media coverage, though. The Phoenix mission is charged with studying the north polar region of Mars to figure out whether or not it could ever have been habitable. Team members hope to make that determination by mission's end, sometime before the end of this calendar year. But, even though it is not assigned the task of looking for life per se, if by some strange Martian chance there were microbes up there in the rusty-red soil, the lander's two microscopes, also on the MECA instrument, do have the resolution power to detect them. Therein, no doubt, is partial cause for so much confused reporting about what Phoenix can and cannot do in the quest to find the ever-elusive ET or Martian microbe. In any case, the reason NASA's public affairs office felt a need to muster an immediate, 48-hour response wasn't so much that the Internet was atwitter with bad blogs and contradicting reports, according to well-placed sources. After all, the big alien snowball had gotten so big, it was destined soon to break apart under the weight of its own wackiness. Rather, the call for public openness was made, because the initial report had come from the vaulted AvWeek and the well-known and respected Covault, and because fingers were pointing that NASA was holding something back. In a conversation earlier today, Covault confirmed that his sources were "reliable," "known and trusted," and were "on both coasts," and "familiar with the Mars exploration program." NASA's Brown denied the Preisdent's science advisor or President had been briefed at the time of Covault's story. "I would assume they have been briefed about this by now," he added during the Tuesday morning press briefing.
Ever since charges of government censorship and the ensuing backlash from the space agency's "editing" of NASA researcher Jim Hansen's data on climate change and global warming in 2005-'06, the agency has been particularly sensitive to any suggestion it might be holding something back. Hansen, who has directed the Goddard Space Flight Center's Institute for Space Studies (GISS) since 1981, is, by most accounts, considered the world's leading Earth climatologist. So, yesterday, at NASA headquarters behest, the Phoenix scientists stepped forward, however reluctantly, and offered up results before peer review or even consensus among all the team members, "an unusual step" and one that "bypasses tradition," as Smith put it. "Talking about the research when its scientists are only about halfway through the data collection phase and have not yet had time to complete data analysis or perform needed laboratory work" is not the normal sequence of events, he said. "But we decided to show the public science-in-action, because of the extreme interest in the Phoenix mission." The Phoenix team had been waiting to announce the discvoery until they could verify it with results from another lander instrumment, the Thermal and Evolved-Gas Analyzer (TEGA), which heats soil samples, then "sniffs" and analyzes gases driven off. The team did get those results and they did not confirm the wet chemistry lab's finding. Late last week, when TEGA analyzed another sample, this one taken from the Snow White trench, looking specifically for chlorine gas. But the data returned Sunday revealed the instrument detected none. "Had we seen it, the identification of perchlorate would be absolutely clear, but in this run we did not see any chlorine gas," said William Boynton, a Phoenix co-investigator and the TEGA lead scientist, of the University of Arizona. "We may have been analyzing a perchlorate salt that doesn't release chlorine gas upon heating," he offered. "But there's nothing in the TEGA data that contradicts MECA's finding of perchlorates."
Back on June 25, TEGA heated a sample of soil dug from the Dodo-Goldilocks trench to high temperature and did detect an oxygen release, Boynton confirmed. Perchlorate could be one of several possible sources of that oxygen, he said. The team could have determined the presence of perchlorates then if the experiment had also detected chlorine. Since the scientists were not expecting perchlorates, however, they did not calibrate their instrument to look for chlorine. Even without the TEGA confirmation, key scientists with the wet chemistry lab and others on the team lab remain convinced that they are seeing the signature of perchlorates and there was enough of a consensus among the other team members, the big mystery discovery was real enough, apparently, to be announced. It was hardly the dramatic kind of news the media had been expecting, much less the discovery for which the public seems to be clamoring, and so the big alien snowball seemed to implode yesterday, splatting with a kind of anti-climactic thud. Given it was only perchlorates, why didn't the MECA team announce their inklings earlier? "When were reported on first soil delivery, we reported what we knew – we had various anomalies," Hecht responded. When they first got the signature for perchlorate, in the Rosy Red soil sample taken from the Dodo-Goldilocks trench on June 25 or Phoenix's Sol 30, "we thought our sensor wasn't working properly," he said. The observation, he said, set off "a flurry of lab work" to convince them their equipment was functioning properly. Then, the MECA team saw the perchlorate signal again in another sample taken from the Snow White trench on Sol 41, July 6, and decided to wait for TEGA's confirmation. "We don't want to come to you and say 'we found chocolate on Mars,' then come back and say, 'We were wrong it was strawberry.' We don't want to do that." More than that, no one on the team really expected to find perchlorates. "Perchlorate caught me by surprise," admitted Smith. "Nobody mentioned the possibilities of perchlorates to me before this. I had to go back to textbooks . . . but we're all learning a lot about perchlorates now."
Perchlorate is an ion, or charged particle, that consists of an atom of chlorine surrounded by four oxygen atoms. It is an oxidant, that is, it can release oxygen. Found naturally on Earth at such places as Chile's hyper-arid Atacama Desert, perchlorates are salts that are quite stable and do not destroy organic material under normal circumstances. Some microorganisms on Earth, in fact, are fueled by processes that involve perchlorates, and some plants concentrate the substance. "A good Earth analogy is the Atacama Desert, where there is a natural accumulation of perchlorates -- and the they accumulate there actually is because it is very, very arid," Richard Quinn, of the SETI Institute, a Phoenix science team member, expounded during a conversation with the Planetary Society afterward. "The perchlorates can be formed on the dust grains in the atmosphere and can also be chemical aerosols, so it's a combination of atmospheric and photochemistry that produces them in the Atacama Desert and it's likely that's the same mechanism that would produce them on Mars," Quinn said. On both planets, they deposit on the surface. "In the desert on Earth, the perchlorates don't go anywhere, because it's very, very dry," Quinn reiterated. Some years back, researchers tried to detect organics or microbial life and found none, he recalled. "After that, other groups found, yes, there are microbes there and irganics. It's just low levels and difficult to detect. It's extreme, but it still supports life. But in terms of it being an extreme environment for life, it's the dryness in the Atacama Desert that makes it extreme, not the presence of perchlorates." A large number of plants on Earth utilize perchlorate, chemist Sam Kounaves, a Phoenix science team member from Tufts University, informed during the press conference. The presence of perchlorate "doesn't indicate anything" that the environment they were examining "would be hostile," to life he assured. "It's another constituent of the soil." The bottom line – though there are still many unknowns – including what kind of perchlorates exactly are there – is that what was found is a relatively inert oxidant. NASA's August 4 press release, which preceded the press conference however, described the possible perchlorate as "a highly oxidizing substance," adding confusion to an already confused situation. "Whoops," responded Quinn.
The perchlorate found on Mars is mild-mannered and mellow, confirmed Hecht. "That frankly is one of the problems when we're rushed into print, people tend to think we're all experts on all things here," he said in a conversation after the conference. "While I wish that was the case, frankly, part of the joy here is we're surrounded by experts. That [press release descriptor] is less than correct. It's an oxidant and not particularly an aggressive one." "On Mars, you would expect it to be fairly benign," Quinn added. "It's not really going to react to anything. Even at Earth temps it would not be very reactive. It is stable. So on Mars, the presence of perchlorate – the perchlorate itself is not necessarily wouldn't be expected to be an inhibitor to life itself." That's because perchlorate as we know and love it is not highly oxidizing until you really heat it up. Then, it's got explosive qualities. "Perchlorate is considered highly oxidizing at high temperatures clarified Quinn. "If you ignite it, it's extremely energetic and exothermic and oxidizing and that's why it can be used as a propellant or rocket fuel," he said. At ambient temperatures on Earth and at Mars temperatures, however, perchlorate is not particularly reactive. "Basically, it has a very high activation energy," Quinn explained. " That's why it's safe to transport it and then be able to use it as a rocket fuel. Perchlorates are highly oxidizing when they're heated up, but at this location on Mars, this perchlorate reacts very, very slowly, if at all at lower temperatures, so it's better to describe it as an oxidant or as being oxidized." The significance is more than a matter of splitting the hairs on wordage. If the perchlorate found on Mars were aggressive, like its cousin peroxide, for example it would likely have considerable impact on the potential for habitability. The notion that peroxide and other oxidizing agents could be at work on Mars, making it all but impossible for life to take hold at least on the surface soil dates back to Viking in the mid-to-late 1970s. "What was shown in the Viking biology experiments is that when the soil was mixed with water the peroxide decomposed," recalled Quinn. "So the reactive component is not very happy – and doesn't have a long lifetime – in environments exposed to water, which is a good thing when it comes to habitability," he noted.
Perchlorate, which may be produced through similar mechanisms as peroxide, is a little different. "It's not reactive in the same way peroxide is," Quinn said. "It's not as aggressive. It is, essentially, stable in water. If you have a soil that contained both peroxide and perchlorate and you wetted it, the peroxide would go away, but the perchlorate wouldn't," he explained. And that's exactly why this discovery of perchlorate is significant enough to have the scientists excited. They must still rule out all other possibilities, including a long shot possibility of contamination from Earth. Although the retro-rocket engines Phoenix used for descent to the Martian surface did not use fuel that contained perchlorates, the fuel that powered the Delta rocket that lifted it into space did. Even so, checkouts and dry runs of the instruments showed that they weren't contaminated, and the scoop has spent more than a month now scraping itself clean gathering and dumping and depositing various soil samples, so any contamination there should be veritably nonexistent. It looks like it's down to Occam's Razor: "All other things being equal, the simplest solution is the best." Right now, the simplest solution is that Phoenix has found perchlorate that resembles the kinds of perchlorate we have on Earth. There are a number of different kinds of perchlorates, each of which can have very different properties, so homing in on precisely what perchlorates are present in the soil will be critical to solving this Martian mystery. So far, such specificity is not yet known. When asked at the press conference, Hecht, quoted Mark Twain: "I was gratified to answer promptly and I said I don't know." The team working on MECA's wet chemistry lab found the signatures for magnesium, sodium, potassium, and probably calcium, "what you'd think of as the usual suspects," Hecht said. "It's anybody's guess which one is dancing with which other one. Eventually, when we put all this stuff together we might be able to tease out information about some of the things we can't directly measure, because in the end everybody has to be dancing with somebody." In any case, this much is certain, "these findings could keep a lot of grad students busy for a long time," he said.
For now, after the media kerfluffle of last weekend, there is "an awful lot of sensitivity on the team about making any announcements about habitability," Hecht said. "We've already been surprised a few times and I can't exclude more surprises. We may discover we're looking at something even more outlandish than we think. This is Mars. Right now, we can say that there isn't anything there that precludes life," reiterated Hecht. That can't be a bad thing. The Phoenix scientists that have been pulled off to deal with Mars' own special brand of woebegone tales are getting back on track to their investigations of the polar region. "Time is short," noted Smith. "We will sample other locations. And we're also thinking about looking under some rocks. There is a lot for us to do." The TEGA scientists will continue to attempt to validate their MECA colleagues' perchlorate discovery and determine its concentration and properties. "It really doesn't limit us in terms of habitability in icy soil," Smith proffered at the end of the conference. "If we're lucky enough to see organic signatures, it would not be too big a surprise. Perchlorate may not be the announcement the media had wanted or the public has long desired. It is not life. But it is an important and interesting discovery that bodes positively for the future of Mars exploration. "Perchlorate is going to be a good marker for water on Mars in the future, because it is stable in water and moves with water," explained Quinn. "That means gradients could tell us a lot about the history of water on the planet. It can show us whether water has been somewhere and whether or not that water has moved or whether there has been water exposure in the environment. That is exciting." "In the bigger picture perspective, it potentially changes the way we think about life on Mars – neither in a bad way or good way," said Hecht, "just a different way."
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